#include <stdio.h>

int main() 
{
    int a = 0;
    int b = 0;
    int c = 0;
    int d = 0;
    scanf("%d %d %d %d",&a,&b,&c,&d);
    
    int x = a > b ? a : b;
    int y = c > d ? c : d;
    printf("%d",(x>y?x:y));
    return 0;
}